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https://github.com/cookiengineer/audacity
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101 lines
2.6 KiB
C++
101 lines
2.6 KiB
C++
/***************************************************/
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/*! \class PRCRev
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\brief Perry's simple reverberator class.
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This class is based on some of the famous
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Stanford/CCRMA reverbs (NRev, KipRev), which
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were based on the Chowning/Moorer/Schroeder
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reverberators using networks of simple allpass
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and comb delay filters. This class implements
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two series allpass units and two parallel comb
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filters.
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by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
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*/
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/***************************************************/
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#include "PRCRev.h"
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#include <math.h>
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using namespace Nyq;
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PRCRev :: PRCRev(StkFloat T60)
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{
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// Delay lengths for 44100 Hz sample rate.
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int lengths[4]= {353, 1097, 1777, 2137};
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double scaler = Stk::sampleRate() / 44100.0;
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// Scale the delay lengths if necessary.
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int delay, i;
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if ( scaler != 1.0 ) {
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for (i=0; i<4; i++) {
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delay = (int) floor(scaler * lengths[i]);
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if ( (delay & 1) == 0) delay++;
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while ( !this->isPrime(delay) ) delay += 2;
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lengths[i] = delay;
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}
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}
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for (i=0; i<2; i++) {
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allpassDelays_[i].setMaximumDelay( lengths[i] );
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allpassDelays_[i].setDelay( lengths[i] );
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combDelays_[i].setMaximumDelay( lengths[i+2] );
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combDelays_[i].setDelay( lengths[i+2] );
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}
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this->setT60( T60 );
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allpassCoefficient_ = 0.7;
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effectMix_ = 0.5;
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this->clear();
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}
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PRCRev :: ~PRCRev()
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{
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}
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void PRCRev :: clear()
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{
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allpassDelays_[0].clear();
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allpassDelays_[1].clear();
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combDelays_[0].clear();
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combDelays_[1].clear();
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lastOutput_[0] = 0.0;
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lastOutput_[1] = 0.0;
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}
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void PRCRev :: setT60( StkFloat T60 )
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{
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combCoefficient_[0] = pow(10.0, (-3.0 * combDelays_[0].getDelay() / (T60 * Stk::sampleRate())));
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combCoefficient_[1] = pow(10.0, (-3.0 * combDelays_[1].getDelay() / (T60 * Stk::sampleRate())));
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}
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StkFloat PRCRev :: computeSample(StkFloat input)
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{
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StkFloat temp, temp0, temp1, temp2, temp3;
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temp = allpassDelays_[0].lastOut();
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temp0 = allpassCoefficient_ * temp;
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temp0 += input;
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allpassDelays_[0].tick(temp0);
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temp0 = -(allpassCoefficient_ * temp0) + temp;
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temp = allpassDelays_[1].lastOut();
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temp1 = allpassCoefficient_ * temp;
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temp1 += temp0;
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allpassDelays_[1].tick(temp1);
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temp1 = -(allpassCoefficient_ * temp1) + temp;
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temp2 = temp1 + (combCoefficient_[0] * combDelays_[0].lastOut());
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temp3 = temp1 + (combCoefficient_[1] * combDelays_[1].lastOut());
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lastOutput_[0] = effectMix_ * (combDelays_[0].tick(temp2));
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lastOutput_[1] = effectMix_ * (combDelays_[1].tick(temp3));
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temp = (1.0 - effectMix_) * input;
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lastOutput_[0] += temp;
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lastOutput_[1] += temp;
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return Effect::lastOut();
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}
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